I have a body, you have a body. We clearly have separate bodies. We are clearly different people. In what way is this separateness an illusion? And what is the value offered by this insight?
From a conservation-of-mass perspective, the atoms that make up our bodies actually came from the dirt. Our mothers ate vegetables that took nutrients (nutrients are just atoms arranged in a particular way) directly from the soil. The nutrients in the vegetables were used by our mothers' bodies to make our bodies. So whatever atoms make up my body actually came from the plant, whose atoms ultimately came from the dirt. The dirt is composed of many things - dead animals and trees, fungi, bacteria, drywall, and airplane parts. So your atoms are also made of all of those things. You and me today are just dirt atoms parading around as humans for a little while. We will all turn back into dirt and the process will continue. Taken from this larger perspective, we are more like waves on the ocean than separate beings. You never look at a single wave and pretend it's not the ocean. Similarly, it's silly to look at a single human and pretend that they are not Earth-dirt. Yes, we are definitely separate beings. But we're also not. And right now, the existential threat of the climate crisis and human-linked ecological destruction is reminding us that we have forgotten our true nature as connected to all things. Humans must work diligently to understand the consequences of our lifestyle choices. In a sustainable society, we are reminded of our connection to each other and to all things. And we feel like we can take good care of those connections.